Socket head adapter These are 3 chrome vanadium steel adapters that fit into the chuck of a drill or screwdriver on which you can fit standard socket heads from any tool kit. The length of each adapter is 5 cm. And the dimensions of the seating place are different, as well as the heads themselves. As a result, you get three sizes of socket heads: 3/8, 1/2 and 1/4 inches.